The cable of a speedometer cable assembly is a rotatable flexible shaft which transmits torque from the vehicle transmission to the speedometer. In original equipment, the cable is usually provided with an integrally formed square at each end, one end of which communicates with the transmission and the other being connected to the speedometer.
Cars and light trucks may be equipped with any one of hundreds of different diameter and/or length cables. Maintaining a stock of such cables with preformed squared ends for aftermarket replacement purposes is not economically desirable to the original equipment manufacturer.
Replacement cable is usually cut from a roll, and hence will have no preformed squared ends. Thus, the use of cable fittings is required. The cable fitting is provided with a squared tip which should have a cross-section identical with the cross-section of the original cable preformed squared end. The cable fitting is readily crimped onto the replacement cable. A replacement cable assembly thus includes a flexible shaft cable, and a cable fitting crimped onto each end thereof. A cable fitting is often referred to as a cable tip.
The casing of the casing assembly is a flexible covering or sheath which protects the cable from dirt, corrosive elements and bruises of various sorts. The casing assembly includes a casing, a ferrule crimped over each end of the casing, and means for attaching the ferrules to the transmission housing and speedometer head respectively. A snap-on type ferrule may be used at the upper, or speedometer end, and a plug type ferrule may be used at the lower, or transmission end. The squared tips of the cable fittings, or portions thereof, are positioned within the outer flared portion of the ferrules.
For one reason or another, either or both assemblies, i.e., cable or casing assemblies, must be replaced from time to time because of damage, malfunction, or wear. Since, as abovementioned, the cables of cable assemblies are so varied, original equipment manufacturers now prefer to fabricate replacement assemblies as they are needed rather than to stock a complete and costly inventory.
Prior art aftermarket casing assemblies are usually made from casings having an inside diameter larger than that of original equipment casings in order that the cable tips can pass therethrough. The clearance between the cable and casing should be kept to a minimum to avoid any "whipping" action therebetween which creates much undesirable noise. As an example, many domestic passenger cars are equipped with cables having a diameter of 0.130 inches. The inside diameter of original casings for such cables is usually 0.135-0.145 inches. Since cable tips could not pass therethrough, it was customary to employ casings having an diameter of 0.170 inches, resulting in considerable increase in noise.
Further, merely duplicating or attempting to duplicate the length of the cable to be replaced did not usually result in a satisfactory replacement cable assembly. It must be borne in mind that replacement cable is ordinarily devoid of any preformed square ends, necessitating the use of cable fittings which results in a shorter cable being required, the length to be deducted depending upon the length to be inserted into both cable fittings. Not infrequently though the cable to be replaced was severed, or severely frayed, rendering attempts to cut duplicate cable lengths quite difficult. Thus, such aforedescribed replacement cables were often of improper length, and prevented proper protrusion of the squared tips of the cable fittings into the transmission and speedometer assemblies. It must be appreciated that even a slightly excessive protrusion of the cable fitting tips into the transmission and/or speedometer assemblies will often cause the cable to bind in the casing. On the other hand, if the squared tips do not protrude sufficiently, inadequate engagement with the mating parts will often result in premature damage or malfunctioning of the tips and/or cable.